Obesity has been recognized as a public health problem in the United States and throughout the world. Overweight or obese individuals are at a higher risk for developing diseases such as hypertension, dyslipidemia, type-2 diabetes (non-insulin dependent diabetes mellitus or NIDDM), coronary heart disease, stroke, gallbladder diseases, osteoarthritis, sleep apnea, and respiratory problems. Obesity is also associated with a higher prevalence of endometrial, breast, prostate and colon cancers. It is therefore not surprising that obesity is also associated with increased mortality and premature death.
The pharmaceutical industry has developed drugs to help people lose weight. However, no drug has been discovered that allows individuals to eat all they desire and retain a sedentary lifestyle while simultaneously losing weight. Furthermore, the drug products available to the general public, whether by prescription or as over-the-counter preparations, are not free of risk. Known risks include valvular heart disease arising out of the use of the combination of fenfluramine and phentermine (Fen-Phen), and irregular heart beat (arrhythmia) that is associated with the use of phenylpropanolamine (PPA). These risks have resulted in bans on the use of these drugs in weight loss products and programs in some countries.
Health risks of anti-obesity preparations are not limited to prescription and/or over-the-counter medications. The use of ephedra in nutritional products employed for weight loss has been associated with arrhythmia and even sudden death in susceptible individuals.
Weight gain is caused by consuming more calories than the body requires for its basal metabolic functions and additional activities in which an individual is involved. The human body stores these excess calories as fatty deposits (lipids in adipose tissue) throughout the body, but is not able to readily access these fatty deposits to satisfy energy needs. To use these stored lipids as an energy source, the number of calories ingested must be less than the total energy expenditure of the body (basal metabolic rate plus activity level). Under hypocaloric conditions the body consumes fat as a source of fuel, but the switch to energy utilization of stored fat is not instantaneous. The body has feedback mechanisms that attempt to preserve existing lipid stores. Therefore, in the interim between the initial reduction in caloric intake and the conversion of lipids to energy, the body consumes lean body mass as a source of energy. Hepatic gluconeogenesis utilizes amino acids from muscle to generate glucose which the body uses as its preferred energy source. Hence, the body will consume some muscle tissue as its energy source during this period of conversion.
The use of lean body mass as an energy source is vitally important to normal physiology and maintenance of energy homeostasis. Under conditions of caloric restriction muscle tissue represents the primary energy source used to maintain the body's basal metabolic rate. However the reduction in lean body mass retards the loss of fat during periods of intentional caloric restriction intended to induce weight loss. Any weight lost as lean body mass represents weight that would otherwise have been lost as fat. The loss of lean body mass can also reduce muscle mass, which is often considered aesthetically and functionally undesirable.
Reduced caloric intake usually induces cravings for food that reduce adherence to weight loss regimens. These cravings are caused by both psychological and physiological mechanisms. For example, ingested carbohydrates are absorbed from the digestive tract into the bloodstream to increase blood glucose levels. In response to the increase in blood glucose, the pancreas releases insulin to aid in the transport of glucose into the cells of the body where glucose is employed as an energy source. However, if the amount of insulin released is greater than the amount of glucose present (which is often the case in overweight individuals), then the body reacts by signaling the brain to ingest more carbohydrates in order to balance the amount of insulin in the bloodstream. This insulin-induced craving for carbohydrates is very common during periods of caloric restriction.
Food cravings can also be attributed to a lack of specific food types. For instance, individuals who attempt to lose weight by eating a high protein, low fat diet often find themselves craving foods that contain fats. Although there are many “fat-free” foods available in commercially available products, they often lack the palatability provided by the presence of fat.
The use of soy protein in combination with soybean fibers, and optionally also in combination with other vitamins and minerals (such as iron, zinc, iodine, manganese, chromium, and selenium), has been described in U.S. Pat. No. 6,268,011.
The use of a chromium salt in nutritional products has been the subject of many patents, for instance, U.S. Pat. Nos. 4,954,492; 5,087,623; 5,175,156; 5,194,615; 6,251,888; 6,251,889; 6,323,192; 6,432,942; and 6,471,998. Some of these patents describe the use of a chromium salt, either alone or in combination with other ingredients, in lowering blood levels of lipids and/or controlling blood glucose levels. U.S. Pat. Nos. 5,087,624; 6,251,889; 6,323,192; 6,432,942; and 6,471,998 describe the use of chromium salts either alone or in combination with other materials for increasing lean body mass. In this latter context, the chromium salt is employed as an anabolic agent to increase muscle mass when taken while following a strength building exercise program. The use of chromium salts in dietary preparations is also described in U.S. Pat. Nos. 6,277,842; 6,399,089; and 6,413,545.
Layman et al. have recently noted that a higher protein diet improves utilization of body fat as an energy source, while reducing (but not eliminating) the loss of lean body mass. J. Nutr. 133:411-417, 2003. Layman has also noted that branched chain amino acids (BCAAs) such as leucine are linked to glucose homeostasis by enhancing recycling of glucose via the glucose-alanine cycle. The BCCAs also enhance translational regulation of muscle protein synthesis through the insulin signaling cascade. Increased leucine concentration is sensed by an element of the insulin-signaling pathway that triggers a phosphorylation cascade that stimulates the translational initiation factors eIF4 and p70s6K. J. Nutr. 133:261S-267S, 2003. Although Layman found that reduced-calorie diets that included protein sources with high endogenous BCAA and leucine content (such as red meat, milk and cheese) did reduce loss of lean body mass, about 12-18% of total weight lost was lean body mass loss.
In spite of extensive prior research, there is still a need for a weight-loss product that helps promote a sensation of satiety to assist with a reduction in caloric intake, while substantially preserving lean body mass as weight loss occurs. Although many researchers have contributed to the complex body of knowledge about physiologic energy utilization under conditions of caloric restriction, existing nutritional supplements and regimens still result in an undesired loss of lean body mass.